Methods and apparatus for power saving in broadcasting carrier information

ABSTRACT

The described aspects include methods and apparatus for activating a transmitter to communicate in a wireless network. A small cell can determine to activate the transmitter to serve user equipment (UE) in a wireless network. The small cell can then broadcast a portion of a set of broadcast signals in a radio frame and broadcast a remaining portion of the set of broadcast signals along with the portion of the set of broadcast signals in a subsequent radio frame. By refraining from immediately broadcasting all broadcast signals, the small cell can mitigate interference to other small cells. In addition, a UE can determine whether to generate random access channel (RACH) sequences for proximity determination or uplink timing synchronization based on parameters received in a RACH order. Moreover, a small cell with an active transmitter can decode discovery signals from a device to facilitate handover determination.

CLAIM OF PRIORITY UNDER 35 U.S.C § 119

The present application for Patent is a divisional of U.S. patentapplication Ser. No. 15/833,619 entitled “METHODS AND APPARATUS FORPOWER SAVING IN BROADCASTING CARRIER INFORMATION” filed Dec. 6, 2017,which is a divisional of U.S. patent application Ser. No. 13/931,346entitled “METHODS AND APPARATUS FOR POWER SAVING IN BROADCASTING CARRIERINFORMATION” filed Jun. 28, 2013, which claims priority to U.S.Provisional Application No. 61/671,029 entitled “METHODS AND APPARATUSFOR POWER SAVING IN BROADCASTING CARRIER INFORMATION” filed Jul. 12,2012, which are assigned to the assignee hereof and hereby expresslyincorporated by reference.

BACKGROUND Field

The present disclosure relates generally to communication systems, andmore particularly, to a method and apparatus for power saving andinterference reduction in broadcasting signals/channels related toopportunistic eNB operations, thereby providing consistent service in awireless communication system.

Background

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power). Examples of such multiple-access technologies includecode division multiple access (CDMA) systems, time division multipleaccess (TDMA) systems, frequency division multiple access (FDMA)systems, orthogonal frequency division multiple access (OFDMA) systems,single-carrier frequency divisional multiple access (SC-FDMA) systems,and time division synchronous code division multiple access (TD-SCDMA)systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example of an emergingtelecommunication standard is Long Term Evolution (LTE).LTE/LTE-Advanced is a set of enhancements to the Universal MobileTelecommunications System (UMTS) mobile standard promulgated by ThirdGeneration Partnership Project (3GPP). It is designed to better supportmobile broadband Internet access by improving spectral efficiency,lowering costs, improving services, making use of new spectrum, andbetter integrating with other open standards using OFDMA on the downlink(DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output(MIMO) antenna technology.

Nodes for providing small coverage cells have been introduced intowireless networks to allow for coverage in desired areas. Such nodes caninclude a relay, a UE relay, a remote radio head (RRH), a femto node, apico node, a micro node, a home evolved Node B (HeNB), a home node B(HNB), or similar devices that can establish a wired or wirelessbackhaul connection to a wireless network and provide service over awireless radio connection. Thus, the nodes can expand coverage of basestations or provide additional service, and a UE can connect to suchsmall cells to receive such service. Small cells can turn off orotherwise refrain from utilizing a transmitter during certain times toconserve radio resources in the wireless network and avoid interferencewith other cells. The small cells can monitor for a discovery signaltransmitted by one or more UEs, and can activate the transmitter basedon detecting such a discovery signal, in one example. In this regard,the small cell can begin transmitting broadcast signals; however, if thesmall cell broadcasts at full power, this can create interference toneighboring cells, possibly causing radio link failure.

Thus, aspects of this apparatus and method provide for power saving andinterference reduction in broadcasting signals/channels related toopportunistic eNB operations, thereby providing consistent service in awireless communication system.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

In accordance with one or more aspects and corresponding disclosurethereof, the present disclosure describes various aspects in connectionwith controlling broadcasting of signals after activating a transmitterin a small cell. For example, some signals, such as reference signals,synchronization signals, or other signals that facilitate detecting thesmall cell can be broadcast before other signals, such as systeminformation signals. In this regard, a UE can detect the small cellbased on the reference/synchronization signals and can reportmeasurements of the small cell for possible handover while the smallcell begins to transmit the other signals. In addition, the small cellcan ramp up power of the signals (e.g., separately for each signal orgroup of signals), and/or ramp up power of signals transmitted in givensubframes over a period of time. Thus, possible interference caused bythe small cell can be managed over the period of time. In addition, inother examples, other interference management techniques can be used fortransmitting the broadcast signals.

In one example, a method for activating a transmitter to communicate ina wireless network is provided. The method includes determining toactivate a transmitter to serve user equipment (UE) in a wirelessnetwork. The method further includes broadcasting a portion of a set ofbroadcast signals in a radio frame and broadcasting a remaining portionof the set of broadcast signals along with the portion of the set ofbroadcast signals in a subsequent radio frame.

In another aspect, an apparatus for activating a transmitter tocommunicate in a wireless network is provided. The apparatus includes aprocessor configured to determine to activate a transmitter to serveuser equipment (UE) in a wireless network. The processor is furtherconfigured to broadcast a portion of a set of broadcast signals in aradio frame and broadcast a remaining portion of the set of broadcastsignals along with the portion of the set of broadcast signals in asubsequent radio frame.

In another aspect, an apparatus for activating a transmitter tocommunicate in a wireless network is provided that includes means fordetermining to activate a transmitter to serve user equipment (UE) in awireless network. The apparatus also includes means for broadcasting aportion of a set of broadcast signals in a radio frame and broadcastinga remaining portion of the set of broadcast signals along with theportion of the set of broadcast signals in a subsequent radio frame.

In yet another aspect, a computer-readable media activating atransmitter to communicate in a wireless network is provided thatincludes machine-executable code for causing at least one computer todetermine to activate a transmitter to serve user equipment (UE) in awireless network. The code may be executable for causing the at leastone computer to broadcast a remaining portion of the set of broadcastsignals along with the portion of the set of broadcast signals in asubsequent radio frame and for causing the at least one computer tobroadcast a remaining portion of the set of broadcast signals along withthe portion of the set of broadcast signals in a subsequent radio frame.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote like elements.

FIG. 1 illustrates an example system for deploying multiple small cellsin a macro node coverage area.

FIG. 2 is a schematic diagram illustrating an example wireless system ofaspects of the present disclosure.

FIG. 3 is a schematic diagram illustrating exemplary aspect of callprocessing in a wireless communication system.

FIG. 4 illustrates an example apparatus for power savings in providingcarrier information.

FIG. 5 illustrates an example apparatus for generating a random accesschannel (RACH) preamble.

FIG. 6 illustrates an example methodology for broadcasting sets ofbroadcast signals following activation of a transmitter.

FIG. 7 illustrates an example methodology for generating a RACHpreamble.

FIG. 8 illustrates an example methodology for receiving discoverysignals from one or more UEs.

FIG. 9 is a block diagram illustrating additional example components ofan aspect of a computer device having a call processing componentaccording to the present disclosure.

FIG. 10 is a diagram illustrating an example of a network architecture.

FIG. 11 is a diagram illustrating an example of an access network.

FIG. 12 is a diagram illustrating an example of a downlink (DL) framestructure in long term evolution (LTE).

FIG. 13 is a diagram illustrating an example of an uplink (UL) framestructure in LTE.

FIG. 14 is a diagram illustrating an example of a radio protocolarchitecture for the user and control planes.

FIG. 15 is a diagram illustrating an example of an evolved Node B and UEin an access network.

DETAILED DESCRIPTION

Various aspects are now described with reference to the drawings. In thefollowing description, for purposes of explanation, numerous specificdetails are set forth in order to provide a thorough understanding ofone or more aspects. It may be evident, however, that such aspect(s) maybe practiced without these specific details.

Described herein are various aspects related to power saving intransmitting signals related to carrier information. For example, a nodeproviding a small cell, referred to herein as a small cell, candetermine to broadcast signals in a wireless network. In one example,the small cell can have deactivated a transmitter pending receipt of adiscovery signal from a user equipment (UE) or other signal to causeactivation of the transmitter and broadcast of the signals. To mitigateinterference caused to other cells, the small cell can initiallybroadcast a portion of a typical set of broadcast channels, and thenbegin transmitting remaining signals in subsequent time periods. In oneexample, the small cell can initially transmit reference and/orsynchronization signals, such that the UE can discover the small celland a source node can begin considering the small cell for handover.Subsequently, the small cell can transmit system information signalsand/or other signals that include information for establishingcommunications with the small cell. The small cell can receiveconfiguration information for such functionality from one or morenetwork components, in a handover message from a source node of the UE,and/or the like.

In addition, the small cell can ramp up power of either portion of thebroadcast signals or individual signals over time, ramp up power ofsignals transmitted in a given subframe, or perform other interferencecancellation techniques to minimize impact of the broadcasts at othercells. Where power of the signals is ramped up over a period of time,the small cell can modify indication of power for some signals. Forexample, cell specific reference signal (CRS) power indicated in systeminformation can be indicated for each step in the power ramping. Inanother example, CRS power can be indicated in system information as aminimum power of the power ramping, an average power, a projection ofpower as received at the UE, a slope of the power ramping, and/or thelike. Moreover, power of other related messages can be modified as well.

Other power savings enhancements related to the carrier information arepresented as well. For example, a source node provides the UE with arandom access channel (RACH) order for the UE to transmit a RACHpreamble to the small cell. The small cell communicates a signal powerof the RACH preamble, which is used by the source node to detect theproximity of the UE to the small cell for uplink timing synchronization.In this example, the UE can transmit the RACH preamble based on the RACHorder or signal parameters provided in a radio resource control (RRC)message.

A small cell, as referenced herein, can include a relay, a UE relay, afemto node, a pico node, a micro node, a home Node B or a home evolvedNode B (H(e)NB), and/or other low power base stations that provide smallcellular coverage areas (e.g., as compared to macro nodes), and can bereferred to herein using one of these terms, though use of these termsis intended to generally encompass any small cell providing node. Forexample, a small cell transmits at a relatively low power compared to amacro node associated with a wireless wide area network (WWAN). As such,the coverage area of the small cell can be substantially smaller thanthe coverage area of a macro base station. Moreover, for example, smallcells can be deployed in user homes, offices, other venues, utilitypolls, public transit, and/or substantially any area to serve a numberof devices. For example, a given small cell may use a smaller scaleantenna array that may be attached to a housing for the base station orto a common mounting platform.

As used in this application, the terms “component,” “module,” “system”and the like are intended to include a computer-related entity, such asbut not limited to hardware, firmware, a combination of hardware andsoftware, software, or software in execution. For example, a componentmay be, but is not limited to being, a process running on a processor, aprocessor, an object, an executable, a thread of execution, a program,and/or a computer. By way of illustration, both an application runningon a computing device and the computing device can be a component. Oneor more components can reside within a process and/or thread ofexecution and a component can be localized on one computer and/ordistributed between two or more computers. In addition, these componentscan execute from various computer readable media having various datastructures stored thereon. The components can communicate by way oflocal and/or remote processes such as in accordance with a signal havingone or more data packets, such as data from one component interactingwith another component in a local system, distributed system, and/oracross a network such as the Internet with other systems by way of thesignal.

Moreover, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” That is, unless specified otherwise, or clearfrom the context, the phrase “X employs A or B” is intended to mean anyof the natural inclusive permutations. That is, the phrase “X employs Aor B” is satisfied by any of the following instances: X employs A; Xemploys B; or X employs both A and B. In addition, the articles “a” and“an” as used in this application and the appended claims shouldgenerally be construed to mean “one or more” unless specified otherwiseor clear from the context to be directed to a singular form.

Various aspects or features will be presented in terms of systems thatcan include a number of devices, components, modules, and the like. Itis to be understood and appreciated that the various systems can includeadditional devices, components, modules, etc. and/or may not include allof the devices, components, modules etc. discussed in connection withthe figures. A combination of these approaches can also be used.

FIG. 1 illustrates an example wireless communication system 100 forhanding over a UE among one or more cells or related nodes. System 100includes a macro base station 102 that provides a coverage area 104within which UEs can connect with macro base station 102 using wirelesscommunications to receive wireless network access. Within and outside ofcoverage area 104, multiple small cells are deployed as well, includingsmall cell 110. The small cells can connect with the wireless networkvia a backhaul (e.g., an X2 interface, a wireless backhaul, an internetbackhaul, etc.), and can provide a coverage cell similar to coveragecell 112 provided by small cell 110 when transmitter is activated andtransmitting broadcast signals. A UE 120 is also shown that can behanded over among macro base station 102 and/or small cells within oroutside of coverage area 104.

According to an example, UE 120 can communicate with base station 102 toreceive wireless network access. The small cells, such as small cell110, can operate with a transmitter powered off or otherwise can refrainfrom broadcasting signals in coverage area 104 so as not to interferewith one another and/or other devices communicating in coverage area104. In this example, UE 120 can transmit a discovery signal or othersignal that can be received by one or more nearby small cells. Thediscovery signal, in one example, can include information regionallyunique to the UE to allow recognition thereof. Moreover, base station102 can command the UE 120 to transmit the discovery signal or otherwiseprovide resources over which to transmit the discovery signal. Smallcell 110, for example, can receive the discovery signal and determinewhether to activate its transmitter to facilitate possible handover ofUE 120 based on the signal. In one example, small cell 110 can determinea strength of the signal, and can activate a transmitter based on thesignal. Thus, UE 120 can detect small cell 110 and report the presenceof small cell 110 in a subsequent measurement report to macro basestation 102 to facilitate a handover determination.

Macro base station 102 can determine whether to handover UE 120 to smallcell 110 based on the measurement report. Macro base station 102 caninitiate handover by preparing the small cell 110 and commanding UE 120to handover thereto. For example, upon activating its transmitter, smallcell 110 can begin transmitting a portion of a set of broadcast signals,while waiting to broadcast a remaining portion of the set of broadcastsignals. In one example, small cell 110 can broadcast reference and/orsynchronization signals (e.g., CRS, primary synchronization signal(PSS), secondary synchronization signal (SSS), etc.) in one or moreradio frames. This allows UE 120 to detect small cell 110 and report asignal strength thereof to base station 102. Base station 102 may thenevaluate small cell 110 as a potential handover candidate for UE 120.

After a period of time (e.g., tens or hundreds of milliseconds (ms)),small cell 110 can begin transmitting a remaining portion of the set ofbroadcast signals in a subsequent radio frame. The remaining portion ofthe set of broadcast signals can include system information signals(e.g., primary broadcast channel (PBCH), system information block (SIB),etc.), along with the initially transmitted portion of the set ofbroadcast signals. In one example, small cell 110 broadcasts theremaining broadcast signals until a handover message is received frombase station 102. In this regard, the system information signals are nottransmitted until the UE 120 is ready to establish connection with thesmall cell 110, thus conserving signaling resources and/or mitigatinginterference in the wireless network.

In addition, for example, small cell 110 can broadcast the signals usingdifferent powers in different subframes to mitigate impact to certainlegacy signals. In another example, small cell 110 can broadcast thesignals by ramping up power over one or more subframes or radio frames,and can ramp up different signals at different rates. The small cell 110can also use other interference management techniques in transmittingthe signals, such as physical cell identifier (PCI) selection, multicastbroadcast over single frequency network (MBSFN) subframe specification,subframe shifting, etc. to mitigate interference of broadcasting thesignals. Moreover, parameters related to the above can be configured tothe small cell 110 via network configuration and/or received in ahandover message. The small cell 110 can indicate power for transmittingcertain signals in system information, for example, and the power can beselected based on information regarding power ramping.

Other enhancements are described as well, such as macro base station 102indicating parameters for communicating a RACH preamble in a RACH orderto the UE 120 based on whether the RACH is being used as proximitydetection in a discovery signal. Furthermore, small cell 110 can refrainfrom receiving discovery signals once its transmitter is activatedand/or can continue to receive and report measurements of the discoverysignals to the macro base station 102 to facilitate handover to smallcell 110.

Referring to FIG. 2, in another aspect, wireless communication system100 includes at least one UE 120 that may communicate wirelessly withone or more small cell 110 over one or more wireless link 125. The oneor more wireless link 125, may include, but are not limited to,signaling radio bearers and/or data radio bearers. Small cell 110 may beconfigured to transmit one or more signals 23 to UE 120 over the one ormore wireless link 125, and/or UE 120 may transmit one or more signals124 to small cell 110. In an aspect, signal 123 and signal 124 mayinclude, but are not limited to, one or more messages, such astransmitting a data packet from the UE 120 to small cell 110.

UE 120 may comprise a mobile apparatus and may be referred to as suchthroughout the present disclosure. Such a mobile apparatus or UE 120 mayalso be referred to by those skilled in the art as a mobile station, asubscriber station, a mobile unit, a subscriber unit, a wireless unit, aremote unit, a mobile device, a wireless device, a wirelesscommunications device, a remote device, a mobile subscriber station, anaccess terminal, a mobile terminal, a wireless terminal, a remoteterminal, a handset, a terminal, a user agent, a mobile client, aclient, or some other suitable terminology.

Additionally, the one or more small cells, including, but not limitedto, small cell 110 of wireless communication system 10, may include oneor more of any type of network component, such as an access point,including a node B, a relay, a peer-to-peer device, an authentication,authorization and accounting (AAA) server, a mobile switching center(MSC), a radio network controller (RNC), etc.

Referring to FIG. 3, in another aspect of the present apparatus andmethod, a wireless communication system 100 is configured to includewireless communications between small cell 110 and UE 120. The wirelesscommunications system may be configured to support communicationsbetween a number of users. The wireless communication system 100 can beconfigured for downlink message transmission or uplink messagetransmission over wireless link 125, as represented by the up/downarrows between small cell 110 and UE 120.

In an aspect, within small cell 110 resides a call processing component140. The call processing component 140 may be configured, among otherthings, to include a signal detecting component 141 capable of receivingand detecting signals from UE 120. In other words, the signal detectingcomponent 141 is configured receive and detect signals from UE 120 overwireless link 125.

In another aspect, the call processing component 140 may also beconfigured to include Tx activation determining component 142 capable ofdetermining to activate a transmitter to serve a UE in a wirelessnetwork. In other words, Tx activation determining component 142 isconfigured to activate a transmitter to serve UE 120 upon receiving anddetecting signals from UE 120.

In yet another aspect, the call processing component 140 may also beconfigured to include broadcasting component 143 capable of broadcastinga portion of a set of broadcast signals in a radio frame. Broadcastingcomponent 143 may also be configured for broadcasting a remainingportion of the set of broadcast signals along with the portion of theset of broadcast signals in a subsequent radio frame. In other words,broadcasting component 143 is configured to broadcast a portion of a setof broadcast signals 154 to UE 120 in a radio frame and broadcast theremaining portion of the set of broadcast signals 154 to UE 120 in asubsequent radio frame over wireless link 125

FIG. 4 depicts an example apparatus 200 for broadcasting carrierinformation in a wireless network. Apparatus 200 can be a small cellthat activates a transmitter based on detecting a discovery signal.Apparatus 200 can include a discovery signal detecting module 210 forobtaining discovery signal from a UE, and a signal broadcasting module212 for transmitting a set of broadcast signals via a transmittingmodule 214. Apparatus 200 can also optionally include a configurationreceiving module 216 for obtaining one or more configuration parametersregarding broadcasting signals, and/or a signal reporting module 218 forcommunicating metrics of a discovery signal to a source node of the UE.

According to an example, transmitting module 214 can remain inactivateat apparatus 200 for a period of time to conserve radio resources andmitigate interference to surrounding nodes. The apparatus 200 can listenfor discovery signals, which can include RACH signals or other definedsignals, from UEs for determining whether to power on the transmittingmodule 214 (e.g., to allow discovery of apparatus 200). Discovery signaldetecting module 210 can receive such a signal from a UE, and candetermine to activate transmitting module 214. This determination can bebased further on comparing a signal quality or strength of the discoverysignal to a threshold, in one example. Once the transmitting module 214is activated, signal broadcasting module 212 can utilize transmittingmodule 214 to transmit one or more broadcast signals.

For example, signal broadcasting module 212 can transmit a portion of aset of broadcast signals in a first radio frame, while transmitting aremaining portion of the set of broadcast signals, along with theportion, in a subsequent radio frame. Thus, not all broadcast signalsneed to be initially transmitted, and radio resources are conserved byholding off on transmitting some of the broadcast signals. In oneexample, signal broadcasting module 212 can initially broadcastreference signals, synchronization signals, or other signals fordetecting apparatus 200, while broadcasting other signals, such assystem or configuration information signals at a later time.

In one aspect detecting apparatus 200 can mitigate possible interferencethat would be caused by immediately transmitting all broadcast signalsupon activation of transmitting module 214. For example, signalbroadcasting module 212 can transmit CRS, PSS, and SSS upon discoverysignal detecting module 210 determining to activate transmitting module214. Thus, the UE can detect the signals for measuring apparatus 200 fora handover determination. Signal broadcasting module 212 can latertransmit PBCH and SIB to allow the UE to configure itself to communicatewith apparatus 200 (e.g., based on a fixed or configured time delay,based on receiving a handover message from a source node of the UE,and/or the like).

Signal broadcasting module 212 can additionally apply power ramping fortransmitting the broadcast signals. In one example, signal broadcastingmodule 212 can apply different power ramping in different subframes soas not to interfere with legacy carrier transmissions. For instance, anew carrier type can specify transmission of CRS, PSS, and SSS every 5ms; thus, signal broadcasting module 212 can transmit these signalsevery fifth subframe, while more slowly ramping up power in othersubframes. In one example, signal broadcasting module 212 can onlytransmit these subframes for a period of time, and then start ramping upthe other signals in between the CRS, PSS, SSS subframes. This can avoidimmediate interference caused by transmitting all signals at full powerwhen determining to activate transmitting module 214. Thus, neighboringcells can start to detect the signals from transmitting module 214 powerramping, and can compensate accordingly to the interference generated bythese signals. Apparatus 200 still transmits CRS and/or PSS/SSS,however, to facilitate detection of apparatus 200.

Ramping up power of the other signals may cause issues for some UEs thatreport control data to apparatus 200, and in this example, the signalbroadcasting module 212 can signal a subset restriction for certaincommunications to connected UEs. For example, the subset restriction cancorrespond to radio link management (RLM), radio resource management(RRM), channel state information (CSI), or similar messages from theUEs. The UEs can receive the restriction and refrain from transmittingsuch messages. Once signal broadcasting module 212 is broadcasting atfull power (or at least a sufficient power), signal broadcasting module212 can signal removal of the restriction to the UEs, allowing UEs totransmit RLM, RRM, CSI, etc., communications.

Additionally, signal broadcasting module 212 can ramp up differentsignals at different speeds. For example, signal broadcasting module 212can ramp up system information signals over a longer period of time, ormore slowly, than reference or synchronization signals. In one example,where signal broadcasting module 212 transmits master information blocks(MIBs) and SIBs are transmitted, the CRS may have a comparable power,but signal broadcasting module 212 may subsequently increase powerfaster for CRS transmissions than MIB/SIB transmissions.

Moreover, signal broadcasting module 212 can introduce additionalinterference cancellation techniques in transmitting the broadcastsignals. For example, signal broadcasting module 212 can select a PCIfor broadcasting the CRS to avoid CRS collision with a source node ofthe UE. In another example, signal broadcasting module 212 can specifysubframes for transmitting CRS as MBSFN subframes to avoid collisionwith the source node. Moreover, in an example, signal broadcastingmodule 212 can shift subframes of the broadcast signals to be offsetfrom those of the source node in a set of subframes. For instance,configuration receiving module 216 can receive the subframes used by thesource node for transmitting the broadcast signals, and can usedifferent subframes (e.g., offset by n subframes). Moreover, forexample, transmitting module 214 can activate and transmit over oneantenna for a period of time before turning on one or more additionalantennas to mitigate interference.

In one example, configuration receiving module 216 can receive one ormore parameters regarding transmitting the broadcast signals uponactivating the transmitting module 214. For example, configurationreceiving module 216 can receive the one or more parameters from atleast one of a local configuration, a configuration from a networkcomponent (e.g. operation, administration, maintenance function (OAM),etc.), a configuration from a source node of the UE (e.g., in a handovermessage where SIB1 delta is signaled), and/or the like. Thus, the one ormore parameters can be received over a wired or wireless backhaul uponregistration of the apparatus 200, upon handover of the UE, at someother point in time, etc. The one or more parameters can specify atleast one of timing for transmitting portions of the broadcast signalsfollowing detecting a discovery signal, power for transmitting theportions of the broadcast signals, power ramping for different signals(e.g., initial power, ramping rate, end power, etc.), power ramping fordifferent subframes, different channel density, carrier type, and/orother parameters related to the described functionality.

Where signal broadcasting module 212 transmits CRS according to rampingpower over a period of time, it can signal the transmit power in a SIB.For example, signal broadcasting module 212 can broadcast a new SIB foreach step in the power ramping of CRS. In another example, where signalbroadcasting module 212 transmits SIB according to a normal transmissionschedule (which can be more infrequent than power steps in the powerramping), signal broadcasting module 212 can indicate a minimum or otherconservative power in the SIB for the CRS, such as an initial power inthe ramping procedure. In another example, signal broadcasting module212 can indicate at least one of a projected received CRS power in theSIB (e.g., based on when the CRS is transmitted with respect to theSIB), an average power of the CRS during power ramping, a slope of thepower ramping, a trend of power ramping at the apparatus 200 or otherapparatuses, and/or the like. Thus, a UE can accordingly determine anexpected power for the CRS in the SIB that is close to or less than theactual power where the SIB is sent less frequently than CRS powerramping steps.

In addition, because the power level calculation may be off at the UEbased on the CRS ramping and indicated power in SIB, a increased rangefor MSG3 adjustment in a RACH procedure can be used to indicate to theUE a power for transmitting MSG3. For example, MSG3 in LTE currently hasa 6 decibel (dB) adjustment range. In one implementation, this can beindicated by 2 bits, where 01=2 dB, 10=4 dB, and 11=6 dB. The possiblevalues can be scaled in this example to a higher range (e.g., 15 dB,where 01=5 dB, 10=10 dB, and 11=15 dB) where needed to convey a largerdifference. Such modifications of the available values can becommunicated in a configuration received by configuration receivingmodule 216 and similarly to a UE for determining power adjustment basedon received indications.

Where transmitting module 214 is active, discovery signal detectingmodule 210 can refrain from detecting discovery signals, as UEs candiscover and be handed over to apparatus 200. In another example,however, discovery signal detecting module 210 can continue to detectsuch signals, and signal reporting module 218 can report related signalmetrics to the source node, such as a signal strength or signal quality,over a wired or wireless backhaul. In this example, the source node candetermine whether to handover the UE to apparatus 200 based on at leastone of the metrics and/or based on loading of the apparatus 200 (whichcan also be indicated by signal reporting module 218), based on traffictype or buffer status of the UE, based on a backhaul condition of theapparatus 200, and/or the like.

FIG. 5 shows an apparatus 300 for differentiating between RACH ordersreceived from a source node. Apparatus 300 can be a UE, for example,that can receive a RACH order from the source node for proximitydetection and/or a RACH order for uplink time synchronization. Apparatus300 can distinguish the RACH orders such to accordingly modifytransmission of the associated RACH preamble. Apparatus 300 includes aRACH order receiving module 310 for obtaining a RACH order from a sourcenode, a RACH preamble generating module 312 for determining a RACHpreamble to transmit to a small cell, and a RACH transmitting module 314for transmitting the RACH preamble. Apparatus 300 can optionally includea RACH configuration receiving module 316 for determining one or moreparameters for determining the RACH preamble.

According to an example, apparatus 300 can be communicating with asource node to receive wireless network access, and RACH order receivingmodule 310 can receive a RACH order from the source node over a physicaldata control channel (PDCCH). RACH preamble generating module 312 candetermine one or more parameters for generating a RACH preamble based inpart on the RACH order. In one example, the RACH order can be receivedover a PDCCH, which can indicate the type of RACH order. In anotherexample, the RACH order can include the one or more parameters (e.g.,using reserved bits indicated in the order). In yet another example, theRACH order can include an indication of whether received RRC parametersare to be used in generating the RACH preamble. In this example, RACHconfiguration receiving module 316 can have previously received the oneor more parameters in an RRC message from the source node or othernetwork component related to proximity detection RACH. Thus, where theRACH order does not indicate to use received RRC parameters or does notinclude parameters in reserved bits, RACH preamble generating module 312can generate a RACH preamble according to uplink timing synchronization.

In any case, where parameters are received and utilized, the one or moreparameters can include a RACH configuration, a RACH sequence, an initialRACH transmit power, an initial RACH timing offset, and/or the like. Forexample, the timings can be set by the source node to avoid collision ofthe apparatus 300 with other UEs transmitting RACH preambles. RACHpreamble generating module 312 in this case can generate a RACH preamblebased on the parameters. RACH transmitting module 314 can accordinglytransmit the appropriate RACH preamble based on the received parametersfor proximity detection or other parameters for uplink timingsynchronization.

Moreover, for example, where RACH preamble generating module 312determines to use one or more parameters related to proximity detectionRACH preambles, RACH transmitting module 314 need not prepare to receiveMSG2 or transmit MSG3 of the RACH procedure because the purpose of theRACH procedure is to send a signal to the small cell to facilitateproximity detection of apparatus 300.

FIGS. 6-8 illustrate example methodologies for power saving related tobroadcasting carrier information. While, for purposes of simplicity ofexplanation, the methodologies are shown and described as a series ofacts, it is to be understood and appreciated that the methodologies arenot limited by the order of acts, as some acts may, in accordance withone or more embodiments, occur in different orders and/or concurrentlywith other acts from that shown and described herein. For example, it isto be appreciated that a methodology could alternatively be representedas a series of interrelated states or events, such as in a statediagram. Moreover, not all illustrated acts may be required to implementa methodology in accordance with one or more embodiments.

FIG. 6 illustrates an example methodology 400 for transmitting a set ofbroadcast signals based on activating a transmitter. In one embodiment,the methodology 400 may be performed by a small cell 110, apparatus 200,etc., described above.

At 402, it can be determined to activate a transmitter to serve UE in awireless network. This can include providing power to the transmitter totransmit one or more broadcast signals. The transmitter can be activatedin response to receiving and processing a discovery signal or othersignals from one or more UEs.

At 404, a portion of a set of broadcast signals can be broadcasted in aradio frame. The portion can include reference signals (e.g., CRS),synchronization signals (e.g., PSS, SSS, etc.), or substantially anysignals that facilitate identifying the transmitter of the signals. Aremaining portion of the broadcast signals, such as system informationsignals (e.g., PBCH, MIB/SIB, etc.) need not be transmitted in the radioframe as it can take time, once the transmitter is identified by a UE,to attempt connection establishment in handover.

At 406, the remaining portion of the set of broadcast signals can bebroadcast, along with the portion of the set of broadcast signals, in asubsequent radio frame. The subsequent radio frame can be tens of ms,hundreds of ms, etc., later than the radio frame. In one example, thesubsequent radio frame can be determined based on receiving a handovermessage from a source node in, or near in time, to the subsequent radioframe (e.g. broadcasting the remaining portion can be in response to thehandover message). This can conserve resources and mitigate interferencethat may otherwise be caused by transmitting all broadcast signalsimmediately upon activating the transmitter.

In addition, a power for transmitting the signals can be ramped up ingiven subframes, ramped up for individual signals, and/or the like.Additional interference cancellation techniques can be performed for thesignals, such as PCI selection, MBSFN subframe specification, subframeshifting, etc. Additionally, configuration parameters for timing, power,etc. can be received from a network component or in a handover message.Furthermore, a power of signals, such as CRS, can be specified in otherbroadcast signals, such as SIB. A minimum, average, slope, trend, etc.can be provided in the SIB, and/or the SIB can be transmitted with eachCRS in the case of ramping up power.

FIG. 7 illustrates an example methodology 500 for generating RACHpreambles based on whether one or more parameters are signaled. In oneembodiment, the methodology 500 may be performed by a UE 120, apparatus300, etc., described above.

At 502, a RACH order can be received from a source node forcommunicating to a target node. The RACH order can include one or moreparameters related to generating a RACH preamble and/or an indication touse one or more previously received parameters to generate the RACH.

At 504, one or more parameters received from the source node related totransmitting according to the RACH order can be determined. For example,the one or more parameters can be indicated by one or more reserved bitsof the RACH order. In another example, the one or more parameters can bepreviously received over RRC. In this example, the RACH order canindicate whether to use the one or more parameters in generating a RACHpreamble. The one or more parameters can relate to a RACH configuration,a RACH sequence, an initial RACH transmit power, an initial RACH timingoffset, and/or the like, and can relate to generating a RACH preamblerelated to proximity detection. If no parameters are indicated, a RACHpreamble related to uplink timing synchronization can be generated.

At 506, a RACH preamble can be transmitted to the target node based onthe one or more parameters. Thus, the RACH preamble for proximitydetection or the RACH preamble for uplink timing synchronization can betransmitted to the target node.

FIG. 8 depicts an example methodology 600 for reporting discovery signalmetrics to a source node. In one embodiment, the methodology 600 may beperformed by a small cell 110, apparatus 200, etc., described above.

At 602, a discovery signal can be received from a UE at a target nodethough a transmitter of the target node is active. The discovery signalsis transmitted to the target node to facilitate activating thetransmitter at the target node to consider the target node as a handovercandidate.

At 604, one or more metrics of the discovery signal can be measured.Such metrics can include a signal quality or strength of the signal.

At 606, the one or more metrics can be reported to a source node tofacilitate handover determination for the UE. Thus, though thetransmitter is active, a small cell, for example, can receive andprocess the discovery signals to facilitate handover determination atsource nodes.

Referring to FIG. 9, in one aspect, small cell 110 of FIGS. 1-3 may berepresented by a specially programmed or configured computer device 900,wherein the special programming or configuration includes callprocessing component 140, as described herein. For example, computerdevice 900 may include one or more components for broadcasting broadcastsignals 153 from small cell 110 to UE 120 to network 12, such as inspecially programmed computer readable instructions or code, firmware,hardware, or some combination thereof. Computer device 900 includes aprocessor 902 for carrying out processing functions associated with oneor more of components and functions described herein. Processor 902 caninclude a single or multiple set of processors or multi-core processors.Moreover, processor 902 can be implemented as an integrated processingsystem and/or a distributed processing system.

Computer device 900 further includes a memory 904, such as for storingdata used herein and/or local versions of applications being executed byprocessor 902. Memory 904 can include any type of memory usable by acomputer, such as random access memory (RAM), read only memory (ROM),tapes, magnetic discs, optical discs, volatile memory, non-volatilememory, and any combination thereof.

Further, computer device 900 includes a communications component 906that provides for establishing and maintaining communications with oneor more parties utilizing hardware, software, and services as describedherein. Communications component 906 may carry communications betweencomponents on computer device 900, as well as between computer device900 and external devices, such as devices located across acommunications network and/or devices serially or locally connected tocomputer device 900. For example, communications component 906 mayinclude one or more buses, and may further include transmit chaincomponents and receive chain components associated with a transmitterand receiver, respectively, or a transceiver, operable for interfacingwith external devices. For example, in an aspect, a receiver ofcommunications component 906 operates to receive one or more data frames52 via a wireless serving node 16, which may be a part of memory 904.

Additionally, computer device 900 may further include a data store 908,which can be any suitable combination of hardware and/or software, thatprovides for mass storage of information, databases, and programsemployed in connection with aspects described herein. For example, datastore 908 may be a data repository for applications not currently beingexecuted by processor 902.

Computer device 900 may additionally include a user interface component909 operable to receive inputs from a user of computer device 900, andfurther operable to generate outputs for presentation to the user. Userinterface component 909 may include one or more input devices, includingbut not limited to a keyboard, a number pad, a mouse, a touch-sensitivedisplay, a navigation key, a function key, a microphone, a voicerecognition component, any other mechanism capable of receiving an inputfrom a user, or any combination thereof. Further, user interfacecomponent 909 may include one or more output devices, including but notlimited to a display, a speaker, a haptic feedback mechanism, a printer,any other mechanism capable of presenting an output to a user, or anycombination thereof.

Furthermore, computer device 900 may include, or may be in communicationwith, call processing component 140, which may be configured to performthe functions described herein.

FIG. 10 is a diagram illustrating an LTE network architecture 1000. TheLTE network architecture 1000 may be referred to as an Evolved PacketSystem (EPS) 1000. The EPS 1000 may include one or more user equipment(UE) 1002, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN)1004, an Evolved Packet Core (EPC) 1010, a Home Subscriber Server (HSS)1020, and an Operator's IP Services 1022. The EPS can interconnect withother access networks, but for simplicity those entities/interfaces arenot shown. As shown, the EPS provides packet-switched services, however,as those skilled in the art will readily appreciate, the variousconcepts presented throughout this disclosure may be extended tonetworks providing circuit-switched services.

The E-UTRAN includes the evolved Node B (eNB) 1006 and other eNBs 1008.The eNB 1006 provides user and control planes protocol terminationstoward the UE 1002. The eNB 1006 may be connected to the other eNBs 1008via an X2 interface (e.g., backhaul). The eNB 1006 may also be referredto as a base station, a base transceiver station, a radio base station,a radio transceiver, a transceiver function, a basic service set (BSS),an extended service set (ESS), or some other suitable terminology. TheeNB 1006 provides an access point to the EPC 1010 for a UE 1002.Examples of UEs 1002 include a cellular phone, a smart phone, a sessioninitiation protocol (SIP) phone, a laptop, a personal digital assistant(PDA), a satellite radio, a global positioning system, a multimediadevice, a video device, a digital audio player (e.g., MP3 player), acamera, a game console, or any other similar functioning device. The UE1002 may also be referred to by those skilled in the art as a mobilestation, a subscriber station, a mobile unit, a subscriber unit, awireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, a client, orsome other suitable terminology.

The eNB 1006 is connected by an S1 interface to the EPC 1010. The EPC1010 includes a Mobility Management Entity (MME) 1012, other MMES 1014,a Serving Gateway 1016, and a Packet Data Network (PDN) Gateway 1018.The MME 1012 is the control node that processes the signaling betweenthe UE 1002 and the EPC 1010. Generally, the MME 1012 provides bearerand connection management. All user IP packets are transferred throughthe Serving Gateway 1016, which itself is connected to the PDN Gateway1018. The PDN Gateway 1018 provides UE IP address allocation as well asother functions. The PDN Gateway 1018 is connected to the Operator's IPServices 1022. The Operator's IP Services 1022 may include the Internet,the Intranet, an IP Multimedia Subsystem (IMS), and a PS StreamingService (PSS).

FIG. 11 is a diagram illustrating an example of an access network 1100in an LTE network architecture. In this example, the access network 1100is divided into a number of cellular regions (cells) 1102. One or morelower power class eNBs 1108 may have cellular regions 1110 that overlapwith one or more of the cells 1102. A lower power class eNB 1108 may bereferred to as a remote radio head (RRH). The lower power class eNB 1108may be a femto cell (e.g., home eNB (HeNB)), pico cell, or micro cell).The macro eNBs 1104 are each assigned to a respective cell 1102 and areconfigured to provide an access point to the EPC 1010 for all the UEs1106 in the cells 1102. There is no centralized controller in thisexample of an access network 1100, but a centralized controller may beused in alternative configurations. The eNBs 1104 are responsible forall radio related functions including radio bearer control, admissioncontrol, mobility control, scheduling, security, and connectivity to theserving gateway 1016.

The modulation and multiple access scheme employed by the access network1100 may vary depending on the particular telecommunications standardbeing deployed. In LTE applications, OFDM is used on the DL and SC-FDMAis used on the UL to support both frequency division duplexing (FDD) andtime division duplexing (TDD). As those skilled in the art will readilyappreciate from the detailed description to follow, the various conceptspresented herein are well suited for LTE applications. However, theseconcepts may be readily extended to other telecommunication standardsemploying other modulation and multiple access techniques. By way ofexample, these concepts may be extended to Evolution-Data Optimized(EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interfacestandards promulgated by the 3rd Generation Partnership Project 2(3GPP2) as part of the CDMA2000 family of standards and employs CDMA toprovide broadband Internet access to mobile stations. These concepts mayalso be extended to Universal Terrestrial Radio Access (UTRA) employingWideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA;Global System for Mobile Communications (GSM) employing TDMA; andEvolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSMare described in documents from the 3GPP organization. CDMA2000 and UMBare described in documents from the 3GPP2 organization. The actualwireless communication standard and the multiple access technologyemployed will depend on the specific application and the overall designconstraints imposed on the system.

The eNBs 1104 may have multiple antennas supporting MIMO technology. Theuse of MIMO technology enables the eNBs 1104 to exploit the spatialdomain to support spatial multiplexing, beamforming, and transmitdiversity. Spatial multiplexing may be used to transmit differentstreams of data simultaneously on the same frequency. The data steamsmay be transmitted to a single UE 1106 to increase the data rate or tomultiple UEs 1106 to increase the overall system capacity. This isachieved by spatially precoding each data stream (e.g., applying ascaling of an amplitude and a phase) and then transmitting eachspatially precoded stream through multiple transmit antennas on the DL.The spatially precoded data streams arrive at the UE(s) 1106 withdifferent spatial signatures, which enables each of the UE(s) 1106 torecover the one or more data streams destined for that UE 1106. On theUL, each UE 1106 transmits a spatially precoded data stream, whichenables the eNB 1104 to identify the source of each spatially precodeddata stream.

Spatial multiplexing is generally used when channel conditions are good.When channel conditions are less favorable, beamforming may be used tofocus the transmission energy in one or more directions. This may beachieved by spatially precoding the data for transmission throughmultiple antennas. To achieve good coverage at the edges of the cell, asingle stream beamforming transmission may be used in combination withtransmit diversity.

In the detailed description that follows, various aspects of an accessnetwork will be described with reference to a MIMO system supportingOFDM on the DL. OFDM is a spread-spectrum technique that modulates dataover a number of subcarriers within an OFDM symbol. The subcarriers arespaced apart at precise frequencies. The spacing provides“orthogonality” that enables a receiver to recover the data from thesubcarriers. In the time domain, a guard interval (e.g., cyclic prefix)may be added to each OFDM symbol to combat inter-OFDM-symbolinterference. The UL may use SC-FDMA in the form of a DFT-spread OFDMsignal to compensate for high peak-to-average power ratio (PAPR).

FIG. 12 is a diagram 1200 illustrating an example of a DL framestructure in LTE. A frame (10 ms) may be divided into 10 equally sizedsub-frames. Each sub-frame may include two consecutive time slots. Aresource grid may be used to represent two time slots, each time slotincluding a resource block. The resource grid is divided into multipleresource elements. In LTE, a resource block contains 12 consecutivesubcarriers in the frequency domain and, for a normal cyclic prefix ineach OFDM symbol, 7 consecutive OFDM symbols in the time domain, or 84resource elements. For an extended cyclic prefix, a resource blockcontains 6 consecutive OFDM symbols in the time domain and has 72resource elements. Some of the resource elements, as indicated as R1202, 1204, include DL reference signals (DL-RS). The DL-RS includeCell-specific RS (CRS) (also sometimes called common RS) 1202 andUE-specific RS (UE-RS) (also known as demodulation reference signals(DM-RS)) 1204. UE-RS 1204 are transmitted only on the resource blocksupon which the corresponding physical DL shared channel (PDSCH) ismapped. The number of bits carried by each resource element depends onthe modulation scheme. Thus, the more resource blocks that a UE receivesand the higher the modulation scheme, the higher the data rate for theUE.

FIG. 13 is a diagram 1300 illustrating an example of an UL framestructure in LTE. The available resource blocks for the UL may bepartitioned into a data section and a control section. The controlsection may be formed at the two edges of the system bandwidth and mayhave a configurable size. The resource blocks in the control section maybe assigned to UEs for transmission of control information. The datasection may include all resource blocks not included in the controlsection. The UL frame structure results in the data section includingcontiguous subcarriers, which may allow a single UE to be assigned allof the contiguous subcarriers in the data section.

A UE may be assigned resource blocks 1310 a, 1310 b in the controlsection to transmit control information to an eNB. The UE may also beassigned resource blocks 1320 a, 1320 b in the data section to transmitdata to the eNB. The UE may transmit control information in a physicalUL control channel (PUCCH) on the assigned resource blocks in thecontrol section. The UE may transmit only data or both data and controlinformation in a physical UL shared channel (PUSCH) on the assignedresource blocks in the data section. A UL transmission may span bothslots of a subframe and may hop across frequency.

A set of resource blocks may be used to perform initial system accessand achieve UL synchronization in a physical random access channel(PRACH) 1330. The PRACH 1330 carries a random sequence and cannot carryany UL data/signaling. Each random access preamble occupies a bandwidthcorresponding to six consecutive resource blocks. The starting frequencyis specified by the network. That is, the transmission of the randomaccess preamble is restricted to certain time and frequency resources.There is no frequency hopping for the PRACH. The PRACH attempt iscarried in a single subframe (1 ms) or in a sequence of few contiguoussubframes and a UE can make only a single PRACH attempt per frame (10ms).

FIG. 14 is a diagram 1400 illustrating an example of a radio protocolarchitecture for the user and control planes in LTE. The radio protocolarchitecture for the UE and the eNB is shown with three layers: Layer 1,Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer andimplements various physical layer signal processing functions. The L1layer will be referred to herein as the physical layer 1406. Layer 2 (L2layer) 1408 is above the physical layer 1406 and is responsible for thelink between the UE and eNB over the physical layer 1406.

In the user plane, the L2 layer 1408 includes a media access control(MAC) sublayer 1410, a radio link control (RLC) sublayer 1412, and apacket data convergence protocol (PDCP) 1414 sublayer, which areterminated at the eNB on the network side. Although not shown, the UEmay have several upper layers above the L2 layer 1408 including anetwork layer (e.g., IP layer) that is terminated at the PDN gateway1018 on the network side, and an application layer that is terminated atthe other end of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 1414 provides multiplexing between different radiobearers and logical channels. The PDCP sublayer 1414 also providesheader compression for upper layer data packets to reduce radiotransmission overhead, security by ciphering the data packets, andhandover support for UEs between eNBs. The RLC sublayer 1412 providessegmentation and reassembly of upper layer data packets, retransmissionof lost data packets, and reordering of data packets to compensate forout-of-order reception due to hybrid automatic repeat request (HARQ).The MAC sublayer 1410 provides multiplexing between logical andtransport channels. The MAC sublayer 1410 is also responsible forallocating the various radio resources (e.g., resource blocks) in onecell among the UEs. The MAC sublayer 1410 is also responsible for HARQoperations.

In the control plane, the radio protocol architecture for the UE and eNBis substantially the same for the physical layer 1406 and the L2 layer1408 with the exception that there is no header compression function forthe control plane. The control plane also includes a radio resourcecontrol (RRC) sublayer 1416 in Layer 3 (L3 layer). The RRC sublayer 1416is responsible for obtaining radio resources (e.g., radio bearers) andfor configuring the lower layers using RRC signaling between the eNB andthe UE.

FIG. 15 is a block diagram of an eNB 1510 in communication with a UE1550 in an access network. In the DL, upper layer packets from the corenetwork are provided to a controller/processor 1575. Thecontroller/processor 1575 implements the functionality of the L2 layer.In the DL, the controller/processor 1575 provides header compression,ciphering, packet segmentation and reordering, multiplexing betweenlogical and transport channels, and radio resource allocations to the UE1550 based on various priority metrics. The controller/processor 1575 isalso responsible for HARQ operations, retransmission of lost packets,and signaling to the UE 1550.

The transmit (TX) processor 1516 implements various signal processingfunctions for the L1 layer (e.g., physical layer). The signal processingfunctions includes coding and interleaving to facilitate forward errorcorrection (FEC) at the UE 1550 and mapping to signal constellationsbased on various modulation schemes (e.g., binary phase-shift keying(BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying(M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded andmodulated symbols are then split into parallel streams. Each stream isthen mapped to an OFDM subcarrier, multiplexed with a reference signal(e.g., pilot) in the time and/or frequency domain, and then combinedtogether using an Inverse Fast Fourier Transform (IFFT) to produce aphysical channel carrying a time domain OFDM symbol stream. The OFDMstream is spatially precoded to produce multiple spatial streams.Channel estimates from a channel estimator 1574 may be used to determinethe coding and modulation scheme, as well as for spatial processing. Thechannel estimate may be derived from a reference signal and/or channelcondition feedback transmitted by the UE 1550. Each spatial stream isthen provided to a different antenna 1520 via a separate transmitter1518TX. Each transmitter 1518TX modulates an RF carrier with arespective spatial stream for transmission.

At the UE 1550, each receiver 1554RX receives a signal through itsrespective antenna 1552. Each receiver 1554RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 1556. The RX processor 1556 implements various signalprocessing functions of the L1 layer. The RX processor 1556 performsspatial processing on the information to recover any spatial streamsdestined for the UE 1550. If multiple spatial streams are destined forthe UE 1550, they may be combined by the RX processor 1556 into a singleOFDM symbol stream. The RX processor 1556 then converts the OFDM symbolstream from the time-domain to the frequency domain using a Fast FourierTransform (FFT). The frequency domain signal comprises a separate OFDMsymbol stream for each subcarrier of the OFDM signal. The symbols oneach subcarrier, and the reference signal, is recovered and demodulatedby determining the most likely signal constellation points transmittedby the eNB 1510. These soft decisions may be based on channel estimatescomputed by the channel estimator 1558. The soft decisions are thendecoded and deinterleaved to recover the data and control signals thatwere originally transmitted by the eNB 1510 on the physical channel. Thedata and control signals are then provided to the controller/processor1559.

The controller/processor 1559 implements the L2 layer. Thecontroller/processor can be associated with a memory 1560 that storesprogram codes and data. The memory 1560 may be referred to as acomputer-readable medium. In the UL, the control/processor 1559 providesdemultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the core network. The upper layerpackets are then provided to a data sink 1562, which represents all theprotocol layers above the L2 layer. Various control signals may also beprovided to the data sink 1562 for L3 processing. Thecontroller/processor 1559 is also responsible for error detection usingan acknowledgement (ACK) and/or negative acknowledgement (NACK) protocolto support HARQ operations.

In the UL, a data source 1567 is used to provide upper layer packets tothe controller/processor 1559. The data source 1567 represents allprotocol layers above the L2 layer. Similar to the functionalitydescribed in connection with the DL transmission by the eNB 1510, thecontroller/processor 1559 implements the L2 layer for the user plane andthe control plane by providing header compression, ciphering, packetsegmentation and reordering, and multiplexing between logical andtransport channels based on radio resource allocations by the eNB 1510.The controller/processor 1559 is also responsible for HARQ operations,retransmission of lost packets, and signaling to the eNB 1510.

Channel estimates derived by a channel estimator 1558 from a referencesignal or feedback transmitted by the eNB 1510 may be used by the TXprocessor 1568 to select the appropriate coding and modulation schemes,and to facilitate spatial processing. The spatial streams generated bythe TX processor 1568 are provided to different antenna 1552 viaseparate transmitters 1554TX. Each transmitter 1554TX modulates an RFcarrier with a respective spatial stream for transmission.

The UL transmission is processed at the eNB 1510 in a manner similar tothat described in connection with the receiver function at the UE 1550.Each receiver 1518RX receives a signal through its respective antenna1520. Each receiver 1518RX recovers information modulated onto an RFcarrier and provides the information to a RX processor 1570. The RXprocessor 1570 may implement the L1 layer.

The controller/processor 1575 implements the L2 layer. Thecontroller/processor 1575 can be associated with a memory 1576 thatstores program codes and data. The memory 1576 may be referred to as acomputer-readable medium. In the UL, the control/processor 1575 providesdemultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the UE 1550. Upper layer packetsfrom the controller/processor 1575 may be provided to the core network.The controller/processor 1575 is also responsible for error detectionusing an ACK and/or NACK protocol to support HARQ operations.

Incorporated is an Appendix A (attached), which describes examplescenarios for power saving in communicating carrier information.

The various illustrative logics, logical blocks, modules, components,and circuits described in connection with the embodiments disclosedherein may be implemented or performed with a general purpose processor,a digital signal processor (DSP), an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof designed to perform thefunctions described herein. A general-purpose processor may be amicroprocessor, but, in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. Additionally, at least oneprocessor may comprise one or more modules operable to perform one ormore of the steps and/or actions described above. An exemplary storagemedium may be coupled to the processor, such that the processor can readinformation from, and write information to, the storage medium. In thealternative, the storage medium may be integral to the processor.Further, in some aspects, the processor and the storage medium mayreside in an ASIC. Additionally, the ASIC may reside in a user terminal.In the alternative, the processor and the storage medium may reside asdiscrete components in a user terminal.

In one or more aspects, the functions, methods, or algorithms describedmay be implemented in hardware, software, firmware, or any combinationthereof. If implemented in software, the functions may be stored ortransmitted as one or more instructions or code on a computer-readablemedium, which may be incorporated into a computer program product.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, substantiallyany connection may be termed a computer-readable medium. For example, ifsoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs usually reproduce data optically withlasers. Combinations of the above should also be included within thescope of computer-readable media.

While the foregoing disclosure discusses illustrative aspects and/orembodiments, it should be noted that various changes and modificationscould be made herein without departing from the scope of the describedaspects and/or embodiments as defined by the appended claims.Furthermore, although elements of the described aspects and/orembodiments may be described or claimed in the singular, the plural iscontemplated unless limitation to the singular is explicitly stated.Additionally, all or a portion of any aspect and/or embodiment may beutilized with all or a portion of any other aspect and/or embodiment,unless stated otherwise.

What is claimed is:
 1. A method for utilizing a random access channel(RACH) process, comprising: receiving a RACH order from a source nodefor communicating to a target node; determining one or more parametersreceived from the source node related to transmitting according to theRACH order; and transmitting a RACH preamble to the target node based onthe one or more parameters.
 2. The method of claim 1, further comprisingreceiving the one or more parameters in the RACH order.
 3. The method ofclaim 1, further comprising receiving the one or more parameters in aradio resource control message from the source node, wherein the RACHorder indicates whether to use the one or more parameters.
 4. The methodof claim 1, wherein the one or more parameters correspond to a RACHconfiguration, a RACH sequence, an initial RACH transmit power, or aninitial RACH timing offset.
 5. An apparatus for utilizing a randomaccess channel (RACH) process, comprising: a processor; a memory inelectronic communication with the processor; instructions stored in thememory, the instructions being executable by the processor to: receive aRACH order from a source node for communicating to a target node;determine one or more parameters received from the source node relatedto transmitting according to the RACH order; and transmit a RACHpreamble to the target node based on the one or more parameters.
 6. Theapparatus of claim 5, the instructions being further executable by theprocessor to receive the one or more parameters in the RACH order. 7.The apparatus of claim 5, the instructions being further executable bythe processor to receive the one or more parameters in a radio resourcecontrol message from the source node, wherein the RACH order indicateswhether to use the one or more parameters.
 8. The apparatus of claim 5,wherein the one or more parameters correspond to a RACH configuration, aRACH sequence, an initial RACH transmit power, or an initial RACH timingoffset.
 9. An apparatus for utilizing a random access channel (RACH)process, comprising: means for receiving a RACH order from a source nodefor communicating to a target node; means for determining one or moreparameters received from the source node related to transmittingaccording to the RACH order; and means for transmitting a RACH preambleto the target node based on the one or more parameters.
 10. Theapparatus of claim 9, further comprising means for receiving the one ormore parameters in the RACH order.
 11. The apparatus of claim 9, furthercomprising means for receiving the one or more parameters in a radioresource control message from the source node, wherein the RACH orderindicates whether to use the one or more parameters.
 12. The apparatusof claim 9, wherein the one or more parameters correspond to a RACHconfiguration, a RACH sequence, an initial RACH transmit power, or aninitial RACH timing offset.
 13. A non-transitory computer-readablemedium comprising code executable by a processor for utilizing a randomaccess channel (RACH) process, the code comprising: code for causing atleast one computer to receive a RACH order from a source node forcommunicating to a target node; code for causing the at least onecomputer to determine one or more parameters received from the sourcenode related to transmitting according to the RACH order; and code forcausing the at least one computer to transmit a RACH preamble to thetarget node based on the one or more parameters.
 14. The non-transitorycomputer-readable medium of claim 13, further comprising code forreceiving the one or more parameters in the RACH order.
 15. Thenon-transitory computer-readable medium of claim 13, further comprisingcode for receiving the one or more parameters in a radio resourcecontrol message from the source node, wherein the RACH order indicateswhether to use the one or more parameters.
 16. The non-transitorycomputer-readable medium of claim 13, wherein the one or more parameterscorrespond to a RACH configuration, a RACH sequence, an initial RACHtransmit power, or an initial RACH timing offset.